Durable-goods orders might soar to record gain. Here’s why.

Orders for big-ticket goods made in the U.S. may have leaped by a record high in July, but don’t be fooled into thinking the economy is soaring as well. A huge gain would be the result of a big bump in demand for expensive Boeing jetliners.

Economists polled by MarketWatch forecast a whopping 12.6% spike in orders for durable goods, with one firm predicting a 38% advance. How big is that? The record increase is 16.6% — set in June 2000.

Yet orders for commercial jets are seldom influenced heavily by the current state of the economy given the long production lag. And planes ordered today may not be assembled for months or years to come, so there’s little immediate effect on the broader economy.

What goes up, in any case, must come down. Boeing is sure to receive a small number of orders in August. That could drag down durable-goods orders for August if the July report is as strong as analysts project.

To get a better idea of how well the broader U.S. manufacturing sector is doing, economists look at new orders for durable goods excluding the aircraft and auto industries. Orders minus transportation are only expected to rise by less than 1% in July.

In other words, businesses continue to spend at a moderate clip that by historical standards is somewhat disappointing five years into an economic recovery.

Another number to keep a close eye on is core capital goods. Orders in that category, which strips out Pentagon spending as well as transportation, are a good proxy for business investment. Companies have been investing at a lackluster pace over the past three years and there’s been little pickup so far in 2014 despite acclerating economic growth.

Also on Tuesday, a report on home prices is likely to show that annual growth slowed down in June thanks to a greater supply of homes for sale. Higher mortgage rates have cut some demand.

S&P/Case-Shiller will release the price barometer at 9 a.m. Eastern. The Federal Housing Finance Agency, which tracks deals involving mortgages backed by Fannie Mae and Freddie Mac, will release its own home-price gauge at the same time.

At 10 a.m., investors will get the latest read on consumer confidence. Economists polled by MarketWatch expect the index to pull back to 88.5 in August after July’s large jump to 90.9, which was the highest level since 2007. Gyrations in the U.S. stock market and rising global conflict may have made Americans feel a little more angst.